Method and apparatus for performing handover procedure

Abstract

The present application relates to a method and an apparatus for performing a handover procedure. One embodiment of the subject application provides a method, which includes: receiving a configuration signaling including first configuration information or second configuration information; determining a first target primary cell (PCell) based on the configuration signaling; and performing a handover procedure to the first target PCell.

What is claimed: 
     
         1 . A method performed by a user equipment (UE), the method comprising:
 receiving a configuration signaling including first configuration information or second configuration information;   determining a first target primary cell (PCell) based on the configuration signaling; and   performing a handover procedure to the first target PCell;   wherein the first configuration information includes information of a first target PCell, information of a set of candidate primary secondary cells (PSCells), and each of the set of candidate PSCells is associated with the first target PCell and is configured with a conditional PSCell addition (CPA) execution condition; and   wherein the second configuration information includes information of one or more candidate PCells, each candidate PCell is associated with a conditional handover (CHO) execution condition, and a candidate PCell among the one or more candidate PCells whose associated CHO condition being met is determined as the first target PCell, and wherein the second configuration information further includes information of one or more sets of candidate PSCells, each candidate PCell is associated with a corresponding set of candidate PSCells, and each candidate PSCell of the one or more sets of candidate PSCells is configured with a CPA execution condition.   
     
     
         2 . The method of  claim 1 , wherein, if the handover procedure to the first target PCell is successful, the method further comprises:
 evaluating the CPA execution condition of each of a set of candidate PSCells associated with the first target PCell.   
     
     
         3 . The method of  claim 1 , wherein, if the handover procedure to the first target PCell is unsuccessful, the method further comprises:
 performing a cell selection procedure based on a predefined criteria to select a cell as a second target PCell among a cell group at least including:   a set of candidate PSCells associated with the first target PCell,   the one or more candidate PCells except the first target PCell, and   each corresponding set of candidate PSCells associated with the one or more candidate PCells.   
     
     
         4 . The method of  claim 3 , further comprising:
 if the second target PCell is included in the cell group, performing a random access channel (RACH) procedure to the second target PCell; or   if the second target PCell is not included in the cell group, performing a radio resource control (RRC) re-establishment procedure to the second target PCell.   
     
     
         5 . The method of  claim 1 , further comprising:
 evaluating the CPA execution condition of each of a set of candidate PSCells associated with the first target PCell during the handover procedure to the first target PCell.   
     
     
         6 . The method of  claim 5 , further comprising:
 determining a candidate PSCell associated with the first target PCell whose associated CPA execution condition being met as a target PSCell; and   performing a RACH procedure to the target PSCell.   
     
     
         7 . The method of  claim 6 , wherein, if the handover procedure to the first target PCell is unsuccessful or a radio link failure occurs in the first target PCell, the method further comprises:
 performing data transmission with the target PSCell or continuing access to the target PSCell without triggering a RRC re-establishment procedure.   
     
     
         8 . The method of  claim 5 , wherein, if none of the CPA execution conditions of each of a set of candidate PSCells associated with the first target PCell is met, the method further comprises:
 continuing to evaluate the CPA execution condition of each of a set of candidate PSCells associated with the first target PCell for a predefined period or until a timer expires.   
     
     
         9 . The method of  claim 5 , wherein, if none of the CPA execution conditions of each of a set of candidate PSCells associated with the first target PCell is met, the method further comprises:
 performing a cell selection procedure based on a predefined criteria to select cell as a second target PCell among a cell group at least including:
 a set of candidate PSCells associated with the first target PCell, 
 the one or more candidate PCells except the first target PCell, and 
 each corresponding set of candidate PSCells associated with the one or more candidate PCells. 
   
     
     
         10 . The method of  claim 9 , further comprising:
 performing a random access channel (RACH) procedure to the second target PCell, the second target PCell is included in the cell group; or   performing a radio resource control (RRC) re-establishment procedure to the second target PCell, the second target PCell is not included in the cell group.   
     
     
         11 . The method of  claim 1 , wherein, if the configuration signaling includes the second configuration information, the method further comprises:
 determining a candidate PCell whose associated CHO execution condition being met as the first target PCell;   determining a candidate PSCell in a set of candidate PSCells associated with the first target PCell whose associated CPA execution condition being met as the target PSCell; and   performing the handover procedure to the first target PCell and performing a RACH procedure to the target PSCell simultaneously.   
     
     
         12 . The method of  claim 11 , wherein, if the handover procedure to the first target PCell is unsuccessful or a radio link failure occurs in the first target PCell, and the RACH procedure to the target PSCell is successful, the method further comprises:
 performing data transmission with the target PSCell without triggering a RRC re-establishment procedure.   
     
     
         13 . The method of  claim 11 , wherein, if the handover procedure to the first target PCell is unsuccessful and the RACH procedure to the target PSCell is ongoing, the method further comprises:
 continuing to access to the target PSCell, or   performing a cell selection procedure based on a predefined criteria to select a cell as a second target PCell among a cell group at least including:
 a set of candidate PSCells associated with the first target PCell, 
 the one or more candidate PCells except the first target PCell, and 
 each corresponding set of candidate PSCells associated with the one or more candidate PCells. 
   
     
     
         14 . The method of  claim 13 , wherein, if the access to the target PSCell is unsuccessful, the method further comprises:
 performing a cell selection procedure based on a predefined criteria to select a cell as a second target PCell among a cell group at least including:
 a set of candidate PSCells associated with the first target PCell, 
 the one or more candidate PCells except the first target PCell, and 
 each corresponding set of candidate PSCells associated with the one or more candidate PCells. 
   
     
     
         15 . The method of  claim 1 , wherein a source master node (MN) determines a CHO execution condition for the candidate PCell, and a candidate MN determines the CPA execution condition for the one or more candidate PSCells. 
     
     
         16 . A user equipment (UE), comprising:
 at least one memory; and   at least one processor coupled with the at least one memory and configured to cause the UE to:
 receive a configuration signaling including first configuration information or second configuration information; 
 determine a first target primary cell (PCell) based on the configuration signaling; and 
 perform a handover procedure to the first target PCell; 
 wherein the first configuration information includes information of a first target PCell, information of a set of candidate primary secondary cells (PSCells), and each of the set of candidate PSCells is associated with the first target PCell and is configured with a conditional PSCell addition (CPA) execution condition; and 
 wherein the second configuration information includes information of one or more candidate PCells, each candidate PCell is associated with a conditional handover (CHO) execution condition, and a candidate PCell among the one or more candidate PCells whose associated CHO condition being met is determined as the first target PCell, and wherein the second configuration information further includes information of one or more sets of candidate PSCells, each candidate PCell is associated with a corresponding set of candidate PSCells, and each candidate PSCell of the one or more sets of candidate PSCells is configured with a CPA execution condition. 
   
     
     
         17 . The UE of  claim 16 , wherein, if the handover procedure to the first target PCell is successful, the at least one processor is configured to cause the UE to:
 evaluate the CPA execution condition of each of a set of candidate PSCells associated with the first target PCell.   
     
     
         18 . The UE of  claim 16 , wherein, if the handover procedure to the first target PCell is unsuccessful, the at least one processor is configured to cause the UE to:
 perform a cell selection procedure based on a predefined criteria to select a cell as a second target PCell among a cell group at least including:
 a set of candidate PSCells associated with the first target PCell, 
 the one or more candidate PCells except the first target PCell, and 
 each corresponding set of candidate PSCells associated with the one or more candidate PCells. 
   
     
     
         19 . A processor for wireless communication, comprising:
 at least one controller coupled with at least one memory and configured to cause the processor to:
 receive a configuration signaling including first configuration information or second configuration information; 
 determine a first target primary cell (PCell) based on the configuration signaling; and 
 perform a handover procedure to the first target PCell; 
 wherein the first configuration information includes information of a first target PCell, information of a set of candidate primary secondary cells (PSCells), and each of the set of candidate PSCells is associated with the first target PCell and is configured with a conditional PSCell addition (CPA) execution condition; and 
 wherein the second configuration information includes information of one or more candidate PCells, each candidate PCell is associated with a conditional handover (CHO) execution condition, and a candidate PCell among the one or more candidate PCells whose associated CHO condition being met is determined as the first target PCell, and wherein the second configuration information further includes information of one or more sets of candidate PSCells, each candidate PCell is associated with a corresponding set of candidate PSCells, and each candidate PSCell of the one or more sets of candidate PSCells is configured with a CPA execution condition. 
   
     
     
         20 . The processor of  claim 19 , wherein, if the handover procedure to the first target PCell is successful, the at least one controller is configured to cause the processor to:
 evaluate the CPA execution condition of each of a set of candidate PSCells associated with the first target PCell.